Brazilian Elodea

Photo credit: Robert Vidéki, Doronicum Kft., Bugwood.org

(Egeria densa)

Species at a Glance

Brazilian elodea is a submerged aquatic perennial that can reach lengths of 3 m (10 ft) or more, and can survive either rooted or free-floating in depths of up to 6.1 m (20 ft). Because of its showy flowers and oxygen generating capabilities, it is widely used as an aquarium plant and is still sold today under its alias “Anacharis”. All introductions in the United States appear to be male plants.

Identification

Leaves: Bright to dark green; densely arranged in whorls of 4-6 leaves per node (note: some lower leaves may occasionally occur in opposite pairs or in whorls of three leaves). The leaves are robust and blade shaped, 1-3 cm

(0.4-1.2 in) long and 5 mm (0.2 in) wide. Leaf margins are very finely toothed (visible only with magnification).

 

Flowers: Large, showy flowers with three white petals, a yellow center, and three green sepals emerge above or at the surface on slender stalks projecting from leaf axils near the stem tips.

 

Stems/Roots: Form irregularly along the stems in areas where two whorls appear to be joined (known as double nodes).

Similar Species

Brazilian elodea may be confused with the invasive plant Hydrilla (Hydrilla verticillata) and the native plant American elodea (Elodea canadensis). Unlike Hydrilla, Brazilian elodea does not have rough teeth on the underside of the leaves and does not produce tubers. American elodea has 2-3 leaves per whorl, which are smaller; usually less than an inch. They also differ significantly by their flowers, with Brazilian elodea being the only one of these species to produce large, attractive white flowers with three petals.

Habitat

In its native range, Brazilian elodea lives in slow-moving and shallow waters. In its invasive range, it can be found in lakes, ponds, sluggish rivers, and streams. It grows best in enriched, somewhat acidic lakes, and prefers substrates of sand, mud, or stone.

Spread

In the past, spread was mostly by aquarium owner and water gardener releases. Since all plants in the United States are male, they can only reproduce vegetatively by plant fragments, which can attach to recreational boats, trailers, and equipment and spread to new water bodies. Once established, it has the ability to cover 100 acres of water per year.

Distribution

Brazilian elodea is native to South America, specifically Brazil and coastal regions of Argentina and Uruguay. It is found to be invasive in several states in the U.S., and in Pennsylvania can be found in the southeast region in Bucks, Montgomery, Delaware, and Philadelphia counties as well as in Allegheny and Bedford counties.

 

Note: Distribution data for this species may have changed since the publication of Pennsylvania's Field Guide to Aquatic Invasive Species (Second Edition 2015), the source of information for this description.

Environmental Impacts

Brazilian elodea grows rapidly (up to 30 cm [11.8 in] in length per day in ideal conditions) and forms mats at the water’s surface. These mats crowd out native species, impede aquatic recreational activities such as boating and fishing, destroy water quality, and make poor habitat for fish. Fragmented pieces can also clog water intake pipes.

The Pennsylvania iMapInvasives Program is a partnership of the Western Pennsylvania Conservancy, the Pennsylvania Natural Heritage Program, and NatureServe.

Funding for Pennsylvania iMapInvasives is provided by the Great Lakes Restoration Initiative.

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Pennsylvania Natural Heritage Program, iMapInvasives partner
Great Lakes Restoration Initiative logo, iMapInvasives funding source